<div>Hello</div>
<style>
    div {
        /*
        border-color: red;
        border-width: 1px;
        border-style: solid;
        */
        /*border: dashed 1px rgb(0, 102, 255);*/
        /*
        border-bottom-color: red;
        border-left-color: green;
        border-top-color: black;
        border-right-color: pink;
        border-top-width: 1px;
        border-bottom-width: 2px;
        border-left-width: 3px;
        border-right-width: 4px;
        border-top-style: solid;
        border-bottom-style: dotted;
        border-left-style: dashed;
        border-right-style: solid;
        */
        /*border-color: red;*/              /* 上下左右red */
        /*border-color: red blue;*/         /* 上下red 左右blue */
        /*border-color: red blue green;*/   /* 上red 右blue 下green 左blue */
        border-color: red blue green gray;   /* 上red 右blue 下green 左gray */
        border-width: 1px 5px 10px;
        border-style: solid dashed;
    }
</style>